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Portulaca oleracea is found ubiquitously in habitats with warm climate (Habtemariam et al., 1993). It has been used as an edible plant by humans since the prehistoric age. In China, the Philippines, Southeast Asia, and Africa, this wild plant is still consumed as food in various ways (Herklots, 1972). P. oleracea is recognized as a quite nutritious vegetable. It includes carbohydrates, amino acids, omega-3 fatty acids (Simopoulos et al., 1992, Mohamed and Hussein, 1994), several vitamins and minerals and many others (Wattenbergs, 1993) (Table 1).
TABLE 1 ______________________________________ Composition of Portulaca oleracea ______________________________________ 1. Noradrenaline 2. Dopa 3. Dopamine 4. Cardiac-glycoside 5. Anthraquinone- glycoside 6. Glucose 7. Sucrose 8. Fructose 9. Coumarin 10. Amino acids 11. Saponins 12. Alkaloids 13. Flavonoids 14. Citric acid 15. Oxalic acid 16. Glutamic acid 17. Asparaginic acid 18. Malic acid 19. Tannic acid 20. Vitamins A, B.sub.1, B.sub.2, C 21. Catechol 22. Urea 23. Wax 24. Batacyanin 25. K-salt (KCI. K.sub.2 SO.sub.4, KNO.sub.3) 26. K.sub.2 O 27. Fe** ______________________________________
In some countries, P. oleracea has been well known for ages as a medicinal herb. It has been used in the treatment of cardiovascular disease in Jamaica and in the topical application for swellings, bruises, abscesses and boils in Nigeria. In addition, it is known to be effective as an expectorant to treat cough (Vemla et al., 1982). It was also used as a "heart-tonic" and a diuretic. There are reports about the analysis of its composition (Tulloch, 1975, Simopoulos et al., 1992, Mohamed and Hussein, 1994), its influence on muscle (Parry et al., 1987, Parry et al., 1993), its effect on antifertility (Verma et al., 1982), and its efficacy in treating blood sugar levels in diabetics (Kin Y, JP 63,208,531, published Aug. 30, 1988).
Several plant products are known for their potential for the prevention and treatment of cancer (Retsas, 1986, Huang et al, 1994, Lau et al 1994). However, the influence of P. oleracea on cancer has not been reported.